Open sketches display in Sketch menu

Consists of 3 commits all squashed up. Used Menu Listener in the end over
polling.
Added a submenu; sketch now comes to front.

Consists of 2 commits all squashed up.
Open Sketches Sub-Menu implementation complete

Current sketch is now indicated with a check box
Merge pull request #2551 from joelmoniz/openSketchList

Implementation of a list of open sketches in the Sketch menu